Zeolites can be used as adsorbents and catalysts or support for catalysts for hydrocarbon conversions. Zeolites have uniform cavities and pores that are interconnected by channels. The sizes and dimensions of cavities and the pores allow for adsorption of molecules of certain sizes. Due to their ability to adsorb molecules through size selections, zeolites have many uses including hydrocarbon conversions, e.g., cracking, hydrocracking, disproportionation, alkylation, oligomerization, and isomerization.
Zeolites that find application in catalysis include any of the naturally occurring or synthetic crystalline zeolites. Examples of these zeolites include large pore zeolites, intermediate pore size zeolites, and small pore zeolites. These zeolites and their isotypes are described in “Atlas of Zeolite Framework Types”, eds. Ch. Baerlocher, L. B. McCusker, and D. H. Olson, Elsevier, Sixth Edition, 2007, which is hereby incorporated by reference. A large pore zeolite generally has a pore size of at least about 7 Å and includes LTL, VFI, MAZ, FAU, OFF, *BEA, and MOR framework type zeolites (IUPAC Commission of Zeolite Nomenclature). Examples of large pore zeolites include mazzite, offretite, zeolite L, VPI-5, zeolite Y, zeolite X, omega, and Beta. An intermediate pore size zeolite generally has a pore size from about 5 Å to less than about 7 Å and includes, for example, MFI, MEL, EUO, MTT, MFS, AEL, AFO, HEU, FER, MWW, and TON frame-work type zeolites (IUPAC Commission of Zeolite Nomenclature). Examples of intermediate pore size zeolites include ZSM-5, ZSM-11, ZSM-22, MCM-22, silicalite 1, and silicalite 2. A small pore size zeolite has a pore size from about 3 Å to less than about 5.0 Å and includes, for example, CHA, ERI, KFI, LEV, SOD, and LTA framework type zeolites (IUPAC Commission of Zeolite Nomenclature). Examples of small pore zeolites include ZK-4, ZSM-2, SAP0-34, SAP0-35, ZK-14, SAP0-42, ZK-21, ZK-22, ZK-5, ZK-20, zeolite A, chabazite, zeolite T, gmelinite, ALP0-17, and clinoptilolite.
Even the smallest changes in pore topology, size and shape can greatly affect sorption selectivity and catalytic activity and selectivity thus new zeolites are highly sought after.